Field of the Invention
The present invention concerns a method and a system for contact-free magnetic navigation of a magnetic body in a work space that is filled at least partially with a fluid. The invention furthermore concerns the use of a thickening agent as an additive for such a fluid.
Description of the Prior Art
Methods and systems of the aforementioned type are used in the medical field. The magnetic body is in the form of an endoscopy capsule. A patient in a work space of the coil system is examined with this endoscopy capsule. In this work space (which is accessible from the outside) the magnetic forces of the coil system act on the magnetic body that is located in the patient and the part of the patient body is introduced into the work space of the coil system. The magnetic body (endoscopy capsule, capsule endoscope) constitutes a probe with which measurements (in particular image exposures) of internal organs of the patient can be made.
The endoscope capsule has a biocompatible housing containing at least one magnetic element for navigation by means of a magnetic field that can be generated by an external magnet system (coil system) and at least one sensor device to detect medically relevant data and/or at least one therapy device to administer a therapeutic agent.
Such an endoscopy capsule (which is also known as a capsule endoscope) is known from DE 101 42 253 C1 and from the corresponding US 2003/0060702 A1, and there is designated as an “endorobot”.
The endorobot known from DE 101 42 253 C1 can be navigated in a hollow organ (for example the gastrointestinal tract) of a patient by means of a magnetic field that is generated by an external magnet system (coil system), i.e. a magnet system arranged outside of the patient. Changes of the orientation of the endorobot in the hollow organ of the patient can be detected and compensated automatically by an integrated system for orientation control that involves a position measurement of the endorobot and an automatic regulation of the magnetic field or the coil currents. Furthermore, the endorobot can be navigated in a targeted manner into desired regions of the hollow organ. This type of capsule endoscopy is therefore also designated as MGCE (Magnetically Guided Capsule Endoscopy).
In a gastroscopy (endoscopically implemented examination of the human or animal stomach) the endoscopy capsule is orally administered to the patient and arrives in the stomach via the esophagus. The expansion of the stomach that is conducted before the oral administration of the endoscopy capsule takes place by means of a fluid that is selectively administered into the stomach of the patient with a stomach probe, or is administered to the patient for independent consumption (drink solution).
During the gastroscopy different quantities, measurement values or samples are taken inside the stomach and provided to a physician or assistant for evaluation. For example, content substances or concentrations of the stomach contents are measured, the chemical composition of the gastric juices is determined or image data of the stomach mucosa are collected.
To transfer measurement and/or image data from the inside of the stomach, the endoscopy capsule is in communication (for example via a radio connection) with a transmission station that is in proximity to the patient. The endoscope capsule can be magnetically navigated accordingly for targeted acquisition of measurement and/or image data from specific regions of the stomach.
The housing of the endoscopy capsule is fashioned either in the shape of an ellipsoid or in the shape of a cylinder, for example. A cylindrical housing has a semi-spherical cap in at least one of its two face-side regions. Both face-side regions of the housing respective have a semi-spherical cap made of an optically transparent material. Such an endoscopy capsule can then respectively have an optical sensor device (CMOS camera or CCD chip, for example) at each of face-side regions.
If, in the MGCE, an endoscopy capsule swims in a fluid, the endoscopy capsule can then already be aligned in space by a relatively weak magnetic field and can be moved in the horizontal and vertical. Since the fluid is typically a normal water, a number of disadvantages are achieved.
Although vertical movement (diving) of the endoscopy capsule in the fluid is possible, there have previously existed no applicable solutions to let the endoscopy capsule float in an arbitrary position between the surface of the fluid and the base of the stomach. Although a manual regulation would be possible under specific requirements, a high image rate would be required in the acquisition of the image data. This can be realized only at a very high cost due to the necessary online transmission during the navigation.
Furthermore, due to physical effects caused by the magnetic forces the endoscopy capsule does not remain stable at a desired position at the fluid surface. The movements of the endoscopy capsule therefore must be manually corrected by the user, which requires a certain amount of practice. A possible solution for stabilization of an endoscopy capsule is a to generate what are known as peak fields, as described in the German Patent Application 10 2008 049 198.5, filed on 26 Sep. 2008. The strong magnetic fields generated by the peak fields can keep the endoscopy capsule stable in the horizontal plane. However, the power consumption increases significantly and only very limited vertical movements of the endoscopy capsule are possible.
Moreover, it can be that the forces exerted on the endoscopy capsule for an intended reverse movement of the endoscopy capsule are not sufficient for this movement since the tip of the endoscopy capsule projects from the fluid (water, for example) and thus the surface tension of the fluid must first be overcome. In order to achieve a solution in these cases, the endoscopy capsule is moistened at its tip with the aid of jerking movements and thus is more easily submerged. However, due to the high velocity with which these measures must be taken, this leads to unusable video images for short periods of time, so the operator of the magnetic coil system may possibly lose his or her orientation.